Low-contrast development of electron micrographs

From the fact that the response of photographic materials conforms to the 'single-hit' expression for exposure to electrons of the energies used in electron microscopy, it follows that the density log exposure curves have a shape substantially independent of the degree of development in conventional solutions. The only way in which the density range corresponding to a given ratio of intensities in the image can be reduced is by reduction of the exposure. The visibility of low-intensity detail in the Image is adversely affected, however. A developer formula is presented with which the density contribution per electron decreases with increasing exposure so that contrast is less than if determined solely by the nature of the exposure. The effectiveness of the solution is demonstrated and practical recommendations are made regarding its use.